Device for drying veneers and plates



Nov. 20, 1962 KAzUYUKl lKEucl-n 3,064,353

DEVICE FOR DRYING VENEERS AND PLATES Filed March 30, 1959 2 Sheets-Sheet 1 INVENTR TTRNEy Nov. 20, 1962 KAzUYUKl lKEucHl 3,054,353

DEvIcE EOP` DRYING vENEERs AND PLATES Filed March 30. 1959 2 Sheets-Sheet 2 l f/v VEN 70H /EZW/ /KMH/ BY W l Y ATTRNEX 3,654,363 Patented Nov. 2G, 1962 fs t i@ 3,064,363 DEVICE FCR DRYING VENEERS AND PLATES Kaznyuk Ikenchi, 107 Miyukcho,-Shizunaicho, Shizunai-gnn, Hokkaido, Japan Filed Mar. 3i), 1959, Ser. No. 362,7@ 1 Ciaim. (Cl. Sli-14S) This invention relates to a device for drying veneers of plywood, synthetic or ber plates,etc.

Usually for plywood manufacturing, a veneer or`plate of around 4.5 mm. -thick is used. When it is first made of 'original wood, it has 30-40% moisture in old wood and "6G-70% moisture in new wood and heartwood contains around 60% more moisture than sapwood. In order to reduce this moisture to 6-7%, ideal for plywood manufacturing, drying operation is necessary. Usually, the following method has been used: a hotblast is sent into a drying room which is kept at a definite temperature and inside this room, the veneer is sent from one place to another by means of a roll dryer till it dries.

Hence, 'it often happens that moisture content is very dierent from one part to another in the same plate. However, regardless of this, drying being performed at ttixed temperature and speed, a veneer havingV a heartwood part and sapwood part together will especially be sub- -ject to warping, deformation or distortion. This is a drawback of the above-mentioned method. Then, a ibinding -agent is applied on both sides of this deformed veneer and taking said piece as a core, it'is heated and Ypressed together with the surface pieces to shape finally the plywood desired. The veneer thus reformed into its normal shape by heating and pressing, returns to its original warped shape as t1me goes on and when it absorbs moisture of the air, warping and distortion are producedron the whole part of plywood and its value, practical as well as commercial, is inevitably greatly decreased.

An object of the invention is to provide a device for drying veneers and plates wherein the material is heated and pressed at the same time on its whole surface by means of a hot table so that a complete straightening and drying of lthe material is performed by the action of steam lon the material and much better 'than in the roller dryer.

An object-of the invention is to provide a device for drying veneers and plates wherein a hot table is provided with a number of air inlet holes communicating with the outside whereby .the material is dried at the moisture content most suitable for plywood, synthetic, ber plates, etc. When it is made into .a product, it is void of any distortion or warping at absorption of moisture from the air.

Other objects and advantages of the invention will appear from the following description of the invention.

For the purpose of illust-rating the invention, there are shown in the accompanying drawings, a form thereof which is at present preferred, although it will be understood that the instrumentalities of which the invention consists may Ibe variously arranged and organized and that the invention is not limited to specific arrangement and organization of the instrumentalities as herein shown and described.

In the drawing:

FIG. l is an elevation of this invention.

FIG. 2 is an enlarged side elevation of a hot table of the invention, with portions broken away;

FIG. 3 is a plan view of FIG. 2 with portions broken away;

FIG. 4 is a side elevation of another embodiment of the invention;

FIG. 5 is a plan view of FIG. 4;

FIG. 6 is a side elevation of still another embodiment;

FIG. 7 is a plan view of FIG. 6; and

FIG. 8 is a plan view of still another embodiment.

Characteristics of the present invention can be deiined as the following: at drying operation, the veneer or pl-ate is heated and pressed at one time by means of a hot table. The water emana-ted from ythe plate is made to be absorbed `from every part of the plate so that each part is drieduniformly at the moisture of 6-7% and deformation and warping is eliminated. Plywood, etc., made of this material and having this as a core, is not subject to deformation nor warping due to moisture absorption from the air, as the `whole article is at a homogeneous moisture content. Moreover, when the material is used as a core, since it keeps its normal shape owing to heating and pressing process, not only can a binding agent be easily applied on it, but also consumpvtion of said binding agent can be largely economized.

Referring to the drawings for more specific details of the invention, FIG. 1 is a diagram explaining heating and pressing of the material a in which the required number of hot tables 1 are superposed on stand 2 alternately with a number of veneers a. On the lower part of the lowermost hot table is provided withY the upper press 3 actuated by an oil pressure device and the upper part of the uppermost hot table is also provided with the lower press 4 so that the plate is pressed from both the upper and lower ends. Said hot table l is provided with a heat-passage 5 nearly in its center, said passage runs -in grate or serpentine form as shown in FIGS. 2 and 3, one end which is fitted with a supply pipe 6, the other end with an exhaustpipe 7. S shows a plug interrupting and closing said passage 5 in the case when the heatpassage 5 is arranged in grate form. Heat given to the supply pipe 6 is discharged from exhaust pipe 7, circulating through the heat-passage 5 so as to heat the hot table 1. 9 shows an exhaust passage tted on both the upper and lower sides of the passage 5 and arranged in grate form or otherwise, each end of which is opened on both sides of the hot ytable l. 10 is an air inlet hole opened to the exhaust passage 9 from the upper and lower surfaces of the hot table l and it is preferably made as many as possible and arranged at small intervals as in the case of the exhaust passage 9. It is also desirable that the air inlet hole 16 =be made small. However, as a matter of fact, it sud-lees that the exhaust passage 9 and the air inlet hole 10 is provided on one surface only of the uppermost and lowermost hot table.

The above-described hot tables are superposed together as shown in FIG. l, so that surfaces provided with air inlet hole l@ face each other. The veneer a to be dried is inserted and pressed between ltwo hot tables and a hot blast is supplied through each supply pipe 6. Thus the material is heated at around C. and at the same time, it is pressed around 40 lbs./in.2 by means of the upper press 3 and the lower press 4. The moisture contained in the plate is evaporated by close contact with the heated hot table and by pressure exerted on said table. Steam is absorbed through a num-ber of air inlet holes 10, enters the exhaust passage 9 and discharged to the outside through each end of the passages opened on each side of the hot table. When it is shown on the meter that the moisture stands at the deinite degrees, heating and pressing are temporarly stopped and a while later a finishing pressing is performed; each of the hot tables 1 is removed and the plate is taken out to dry.

In the above-mentioned operation, moisture content of each part of the plate heated and pressed, is different one from the other. However, as heating goes on, the drying degree of small moisture part becoming higher and heat conductivity smaller, evaporation of the water remaining on this part becomes weaker. On the other hand, as big moisture part is fully heated, evaporation is very active here. Steam goes Vtoward the exhaust passage, 9 facing and communicating with said small moisture part so that nothing prevents evaporation from big moisture part. On the contrary, evaporation from small moisture part being suppressed by a large amount of steam in the exhaust passage 9 facing said par-t, evaporation is performed from each part of the plate according to its moisture content and evaporated water is discharged without delay. Therefore, every pa-rt of the plate can be dried at uniform moisture content, neither more or less. It is to be added that in this invention, the whole surface of the pla-te is pressed simultaneously instead of a part of it as in aroller dryer. Hence, the plate is straightened into normal shape and the plate a thus dried will not be subject to deformation nor Warping, even when it is exposed to the outside and absorbs moisture, since every part is uniformly dried.

FIG. 4 and the following show another application mode wherein the hot table is consisted of two parts:

one part has a heat-passage 5, the other part has an air inlet hole 10. These two parts are made separately and then jointed together to form a hot table used for the same purpose. In the modification shown in FIGS. 4 and 5, a bearing table 11 provided with an exhaust passage 9 and air inlet hole iii are fitted to the machine. Said bearing table 11 is jointed on both surfaces or one surface of the table 12 provided with heat-passage 5. Those shown in FIGS. 6 and 7 is a bearing table 11 providing with channel 13 running in grate form, said channel 13 is superposed on the table 12 and uses the former as exhaust passage in order to facilitate manufacturing of the hot table. FIG. 8 shows the case wherein the channel 14 -runs in straight lines instead of in grate form. The working of these are the same as those shown in FIGS. 2 and 3.

As explained in the foregoing specification, this invention is especially useful for drying veneers and plates for plywood and others lby means of a hot table provided with a number of air inlet holes on rthe whole contact surface of the material and also with an exhaust passage communicating with said hole, thereby steam produced at heating is made to be absorbed from the whole surface of the material and completely eliminated.Y This enables manufacturing of superior plywood and Vothers void of deformation, distortion or warping, sinceevery part of the material is made to dry so that every part of the material is at a uniform and ideal moisture content.

The present invention may be embodied in other specific forms without departing from the spirit thereof. It is therefore desired that the present embodiments be considered in all respects as illustrative and not restrictive, reference being had to ythe appended claim rather lthan to foregoing description -to indicate the scope o'f the invention.

What is claimed is:k

Apparatus for simultaneously drying a plurality of sheets of material such as veneers or the like comprising a press including a pair of spaced, parallel pressure surfaces for imposing a constant pressure on a stackof sheets and heating-and-moisture exhaust plates, a stack of planar heating-and-moisture removal plates disposedY in juxtaposed relation between said pressure surfaces for receiving between alternate plates sheets to lbe dried; the improvement comprising one of said plates including opposed contact surfaces and a heating passa-ge disposed in a plane parallel to said contact surfaces, said heating passage comprising a plurality of irst linear passage segments disposed in parallel relation and uniformly spaced from each other, and a plurality of second linear passages disposed normal to and communicating with said :first linear passage segments and uniformly spaced from each other, said one plate including at opposite Sides thereof a plurality of uniformly disposed exhaust orices normal to said contact surfaces, exhaust passages disposed between said contact surfaces and said heating passage in communication with said orifices and having a substantially greatercross-sectional area than the crosssectional area of said orifices, for drawing off water vapor from sheets of material that each of said contact surfaces contact during the application of heat and pressure, said exhaust passages comprising a plurality of first linear exhaust passage segments disposed in parallel relation and uniformly spaced from each other, and a Yplurality of second linear passage segments disposed nor mal to and communicating with said tirst linear exhaust passage segments and uniformly disposed with respect V4to each other, said first and second exhaust passage segments being disposed intermediately and centrally of the respective first and second heat passage segments in a plane normal to said contact surfaces.

References Cited in the tile of this patent UNITED STATES PATENTS Pfeffer May 18,1875

163,403 2,094,862 weich ocr. s, 1937 2,332,886 Basler ocr. 26, 1943 Auml 

